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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
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    <title>Document</title>
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<body>
    
</body>
<script src="browser.js"></script>
<script type="text/babel">
    let a =10;
    let b=20;

    console.log(a+b)
    alert(a+b)

</script>
<script type="text/javascript">

	var obj ={}
	var obj1={}
	
	var num=11;
	var num1=11;
	function show(){
		return   
	}
    console.log(typeof null)//
    console.log(typeof 11)//
    console.log(typeof "null")//
    console.log(typeof undefined)
    console.log(typeof NaN)//
    console.log(typeof -Infinity)// 
    console.log(typeof obj)
    console.log(typeof show)//
    console.log(typeof show())//
    console.log(null == undefined)//            隐式转换  强制类型转换与隐式类型转换
    console.log(NaN==NaN)//                     js当中唯一自身不等于自身  NaN
    console.log(obj==obj)
    //引用数据类型   指向内存中对象存储的首地址
    console.log(obj==obj1)
    //基本数据类型  值
    console.log(num==11)
    console.log(num==num1)

</script>
</html>